Current share compensation design

ABSTRACT

A current share system for providing current to a load includes a first power supply module that controls a first voltage converter to provide a first current to the load, that transmits synchronization information using a first pin, and that transmits at least one second type of information using the first pin. A second power supply module receives the synchronization information at a second pin, receives the at least one second type of information at the second pin, and controls a second voltage converter to provide a second current to the load based on the synchronization information and the at least one second type of information.

FIELD

The present disclosure relates to control systems for power supplies,and more particularly to systems and methods for current sharing betweenDC to DC converters.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

A power supply outputs a predetermined voltage that may be used to powerone or more components. For example, the predetermined voltage may powerone or more components of an integrated circuit (IC). In somesituations, however, a voltage that is less than the predeterminedvoltage may be sufficient. The lower voltage may be obtained from thepredetermined voltage using a voltage divider circuit. Voltage dividercircuits, however, are inefficient and inaccurate.

The power supply may implement a DC to DC converter (such as astep-down, or “buck,” converter) to provide the lower voltage. Under agiven set of conditions, a buck converter is generally more efficientand more accurate than a voltage divider circuit. A buck converter mayinclude an inductor, a capacitor, and two switches. The buck converteralternates between charging the inductor by connecting the inductor tothe predetermined voltage and discharging the inductor to a load.

Two or more single phase power supplies may be stacked (i.e., providedin parallel) to minimize a required input capacitance, increase outputpower, reduce thermal stress, and lower inductor height. Each of thepower supplies provides current during a respective phase.

SUMMARY

A current share system for providing current to a load includes a firstpower supply module that controls a first voltage converter to provide afirst current to the load, that transmits synchronization informationusing a first pin, and that transmits at least one second type ofinformation using the first pin. A second power supply module receivesthe synchronization information at a second pin, receives the at leastone second type of information at the second pin, and controls a secondvoltage converter to provide a second current to the load based on thesynchronization information and the at least one second type ofinformation.

In other features, a digital signal includes the synchronizationinformation and the at least one second type of information. The secondtype of information includes at least one of current sharinginformation, duty cycle information, and commands. The second type ofinformation includes duty cycle information, and the second power supplymodule adjusts a duty cycle of the second voltage converter based on theduty cycle information. The synchronization information includessynchronization pulses and the second type of information includes aframe of data. The frame of data is transmitted using consecutive onesof the synchronization pulses.

In other features, at least one second type of information includescurrent sharing information corresponding to the first current. Thesecond power supply module receives the current sharing information,receives a signal corresponding to the second current, and adjusts thesecond current based on the current sharing information and the signal.The second power supply module adjusts the second current further basedon an output stage resonance frequency of the current share system. Thesecond power supply module includes a proportional-integral (PI) controlmodule that adjusts the second current, and a proportional gain of thePI control module is selected such that a zero of the PI control modulematches an output stage resonance frequency of the current share system.To simplify the design of the PI controller, an integral gain of the PIcontrol module is set to 1.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example current share systemincluding DC to DC buck converters according to the present disclosure;

FIG. 2 is a functional block diagram of an example of current sharesystem according to the present disclosure;

FIG. 3 is a functional block diagram of an example current share controlmodule according to the present disclosure; and

FIG. 4 is a flowchart illustrating steps of an example current sharemethod according to the present disclosure.

DETAILED DESCRIPTION

The following description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Forpurposes of clarity, the same reference numbers will be used in thedrawings to identify similar elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A or Bor C), using a non-exclusive logical or. It should be understood thatsteps within a method may be executed in different order withoutaltering the principles of the present disclosure.

As used herein, the term module may refer to, be part of, or include anApplication Specific Integrated Circuit (ASIC); an electronic circuit; acombinational logic circuit; a field programmable gate array (FPGA); aprocessor (shared, dedicated, or group) that executes code; othersuitable components that provide the described functionality; or acombination of some or all of the above, such as in a system-on-chip.The term module may include memory (shared, dedicated, or group) thatstores code executed by the processor.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared, as used above, means that some or allcode from multiple modules may be executed using a single (shared)processor. In addition, some or all code from multiple modules may bestored by a single (shared) memory. The term group, as used above, meansthat some or all code from a single module may be executed using a groupof processors. In addition, some or all code from a single module may bestored using a group of memories.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

Two or more single phase power supplies may be stacked such that eachpower supply provides current during a respective phase. In other words,the power supplies operate in a current sharing mode. In the currentsharing mode, current and power provided to a common load are sharedamongst the power supplies.

Each of the power supplies may have different operating characteristicsthat prevent current from being equally shared amongst the powersupplies, resulting in a current imbalance. For example only, variationsin component tolerances, offsets, environmental conditions, andconnections between the power supplies and the common load may causevariations between the currents provided in each phase, and consequentlycause the current imbalance.

A current share system of the present disclosure implements asynchronization (sync) control module that communicates with each of thepower supplies in a current share arrangement. For example only, one ormore of the power supplies may include the sync control module. One ofthe power supplies including the sync control module may be a masterpower supply module and the remaining power supplies may be slave powersupply modules. The master power supply module uses the sync controlmodule to transmit information to the slave power supply modules. Theinformation may include, but is not limited to, sync information,current sharing information, duty cycle information, and commands. Eachof the slave power supply modules may correct any current offset orimbalance between the master power supply module and the slave powersupply modules based on the information.

Referring now to FIG. 1, an example implementation of a current sharesystem 100 is shown. Although the current share system is shownimplementing DC to DC buck converters, other suitable converters may beused. For example only, the current share system may implement a voltageregulator module (VRM) or a linear regulator. The current share system100 includes power supply modules 102, including a master power supplymodule 102-1 and n slave power supply modules 102-n, where n is greaterthan 0 and the current share system provides current in n+1 phases. Eachof the power supply modules 102 corresponds to a different one of then+1 phases. For example only, the master power supply module 102-1provides current to a buck converter 104-1 during a first phase and theslave power supply module 102-n provides current to a buck converter104-n during an (n+1)th phase.

A DC power source 110 inputs DC power to the power supply modules 102and the buck converters 104. A voltage input to the buck converters 104will be referred to as an input voltage (V_(IN)) 112. The buckconverters 104 may each include a switching module 116 (e.g. 116-1 and116-n), an inductor 124 having an inductance L and a DC resistance R_(L)(e.g. 124-1 and 124-n), and a capacitor (C) 128 (e.g. 128-1 and 128-n).Alternatively, the buck converters 104 may function with a single commoncapacitor (not shown) instead of the capacitors 128-1 and 128-n. Thebuck converters 104 output DC power to a common load 136. The voltageoutput by the buck converters 104 may be provided as an output voltage(V_(OUT)) 140, which may be provided as a feedback voltage (V_(FB)) 142to each of the power supply modules 102. The current through the load136 will be referred to as a load current (I_(LOAD)) 144. The masterpower supply module 102-1 may function with an optional externaloscillator (not shown).

Each of the switching modules 116 includes a first switch 148 (e.g.148-1 and 148-n) and a second switch 152 (e.g. 152-1 and 152-n). Forexample only, the first and second switches 148 and 152 may be fieldeffect transistors (FETs) as shown in the example of FIG. 1. In variousimplementations, such as in the example of FIG. 1, the first and secondswitches 148 and 152 may be p-type, enhancement FETs. The first and/orthe second switch 148 and 152 may be another suitable type of switch.

In the example of FIG. 1, a source terminal of the first switch 148 isconnected to the input voltage 112, and a drain terminal of the firstswitch 148 is connected to a source terminal of the second switch 152.The drain terminal of the second switch 152 is connected to ground. Afirst end of the inductor 124 is connected to a node 156 between thedrain terminal of the first switch 148 and the source terminal of thesecond switch 152. A voltage at the node 156 (e.g. 156-1 and 156-n) willbe referred to as a switching voltage (V_(SW)). A second end of theinductor 124 is connected to a first end of the capacitor 128. A secondend of the capacitor 128 may be connected to ground.

The feedback voltage 142 may be measured at a node between the inductor124 and the capacitor 128. The switching module 116 controls connectionand disconnection of the inductor 124 and the input voltage 112. Gateterminals of the first and second switches 148 and 152 are connected tothe power supply modules 102. The power supply modules 102 controloperation of the first and second switches 148 and 152. The power supplymodules 102 control first and second switches 148 and 152 using pulsewidth modulation (PWM). More specifically, the power supply modules 102generate first and second PWM signals 184 (e.g. 184-1 and 184-n) and 188(188-1 and 188-n) that are applied to the gate terminals of the firstand second switches 148 and 152, respectively.

The power supply modules 102 vary the duty cycle of the first and secondPWM signals 184 and 188 to control the output of the buck converters104. The duty cycle of a signal may refer to a percentage of apredetermined period (e.g., a control loop) during which the signal isin an active state. For example only, the power supply modules 102 maymonitor the feedback voltage 142 to control the first and second PWMsignals 184 and 188 to maintain the output voltage 140 at approximatelya predetermined (e.g., commanded or desired) voltage. The predeterminedvoltage is less than the input voltage 112.

The master power supply module 102-1 transmits information associatedwith the operation of the current share system 100 to the slave powersupply module 102-n. For example, each of the power supply modules 102controls a corresponding one of the buck converters 104 to provide atarget current. However, in some instances, while the master powersupply module 102-1 accurately provides the target current, the slavepower supply module 102-n may provide a current that is greater than orless than the target current, or offset from the target current.Accordingly, the information received from the master power supplymodule 102-1 allows the slave power supply module 102-n to make controladjustments to provide a current consistent with the target current andthe master power supply module 102-1.

For example only, the information transmitted to the slave power supplymodule 102-n includes, but is not limited to, sync information, currentsharing information, duty cycle information, and commands. For exampleonly, the sync information may include a sync pulse to synchronizephases of the power supply modules 102. The current sharing informationmay indicate the target current, which may correspond to a currentthrough the inductor 124-1 of the buck converter 104-1 (i.e. a masterinductor current). The duty cycle information may include a commandedduty cycle. The commands may include power on and power off commands.

The master power supply module 102-1 transmits the information using asingle pin 194 (e.g. over a single wire). More specifically, the masterpower supply module 102-1 transmits multiple types of information, suchas the sync information, the current sharing information, the duty cycleinformation, and the commands, using the single pin 194. Similarly, theslave power supply module 102-n receives the multiple types ofinformation using a single pin 196. The slave power supply module 102-nretrieves the sync information to synchronize control with the masterpower supply module 102-1.

For example only, the slave power supply module 102-n may respond to async pulse included in the information. Similarly, the slave powersupply module 102-n retrieves the current sharing information, the dutycycle information, and the commands to adjust control of the buckconverter 104-n accordingly. The presence of the connection between thesingle pins 196 and 194 may indicate to the slave power supply module102-n that the slave power supply module 102-n is operating as a slavein a current share arrangement. For example only, the slave power supplymodule 102-n may detect the sync pulse on the pin 196 and determine thatthe slave power supply module 102-n is in the current share arrangement.

Referring now to FIG. 2, an example current share system 200 includes amaster power supply module 204 and a slave power supply module 208 shownin further detail. Although as shown in FIG. 2 only a single slave powersupply module 208 is shown (i.e. in a two phase arrangement), thecurrent share system 200 may include any number of slave power supplymodules. Each of the master power supply module 204 and the slave powersupply module 208 includes: a sync control module 212 (e.g. 212-1 and212-2); a converter control module 216 (e.g. 216-1 and 216-2); a commandmodule 220 (e.g. 220-1 and 220-2); a reference oscillator 224 (e.g.224-1 and 224-2); and an inductor current measurement module 228 (e.g.228-1 and 228-2).

The master power supply module 204 and the slave power supply module 208are shown to further include a current share control module 232 (e.g.232-1 and 232-2), which is associated with operation as a slave in thecurrent share system 200. The current share control module 232-2 updatesthe converter control module 216-2 with current sharing informationreceived from the master power supply module 204. The slave power supplymodule 208 (and optionally, the master power supply module 204) may beprogrammed with or receive an offset 236 (e.g. 236-1 and 236-2). Theoffset 236 may correspond to a user calibrated or manufacturer selectedphase delay of the slave power supply module 208 with respect to themaster power supply module 204. In other words, the offset 236 maycorrespond to a potential offset between the circuitry of the masterpower supply module 204 and the slave power supply module 208, and mayreflect how quickly and efficiently the current share control module232-2 removes any offset and balances the currents.

Only the current share control module 232-2 and the offset 236-2 of theslave power supply module 208 may be active in the current share system200 as shown. However, it is to be understood that the master powersupply module 204 may still include the current share control module232-1 and receive the offset 236-1. For example only, the master powersupply module 204 may be configured to operate as a slave in anothercurrent share arrangement. Conversely, the slave power supply module 208may be configured to operate as a master in another current sharearrangement.

Accordingly, the master power supply module 204 may include anynecessary components configured for operating as a slave, and the slavepower supply module 208 may include any necessary components configuredfor operating as a master. As such, the master power supply module 204and the slave power supply module 208 may be interchangeable.

The sync control module 212-1 communicates with the sync control module212-2 to provide information to the slave power supply module 208. Forexample only, the sync control module 212-1 serially transmitsinformation such as sync information, current sharing information, dutycycle information, and commands using a single pin or wire 240. The synccontrol module 212-2 serially receives the information using a singlepin or wire 244. For example only, each of the sync control modules212-1 and 212-2 may implement a transmitter and receiver (i.e. atransceiver) for both transmitting and receiving information.

The converter control modules 216 each control operation of a respectiveconverter (for example only, a respective one of the converters 104 asshown in FIG. 1). For example only, the converter control modules 216control operation of the respective converters 104 using signals 248(e.g. 248-1 and 248-2), each of which may correspond to the signals 184and 188 as shown in FIG. 1. Each of the converter control modules 216may include PWM time base modules, PLLs, and/or other circuitry (notshown) associated with PWM control of the converters 104.

The sync information allows the phases of the master power supply module204 and the slave power supply module 208 to be synchronized. Forexample only, it may desirable for operation of the master power supplymodule 204 and the slave power supply module 208 to begin at the sametime so that the respective phases of the power supply modules 204 and208 are aligned. Accordingly, the sync information may include a syncpulse that indicates to the slave power supply module 208 when to beginoperation of the converter control module 216-2. For example only,during or after an initial power up, the sync control module 212-1transmits the sync pulse to the sync control module 212-2, and each ofthe master power supply module 204 and the slave power supply module 208begin operation of the respective converter control modules 216-1 and216-2 according to the sync pulse.

In addition to the sync pulse, the sync control module 212-1 transmitsat least one second type of information to the sync control module 212-2using the same single wire 240. The second type of information mayinclude, but is not limited to, the current share information, the dutycycle information, and the commands. For example only, the second typeof information is digital data implementing the same digital signalstructure as the sync pulse. In other words, if the sync pulse uses asquare wave digital signal (e.g. the sync pulse is a single square wavebit), then the second type of information is implemented using a squarewave digital signal having the same bit characteristics as the syncpulse. For example only, the second type of information may includepacketized data (i.e. a frame of data) that is transmitted after thesync pulse or in between consecutive sync pulses.

The digital data transmitted from the sync control module 212-1 to thesync control module 212-2 may indicate which data corresponds to thesync pulse and which data corresponds to the second type of information.For example only, the sync pulse may follow a predetermined sequence ofbits (e.g. a predetermined number of 1's or 0's). A frame of dataincluding any of the second type of information may immediately followthe sync pulse. After the frame of data is transmitted, thepredetermined sequence of bits may be transmitted again to indicateanother upcoming sync pulse. It is to be understood that other suitablemultiple access schemes may be used to integrate the transmission of thesync pulse and the second type of information using the same wire 240.

Each frame of data may include the current sharing information, the dutycycle information, and/or the commands. Alternatively, a first frame ofdata transmitted after a first sync pulse may include the currentsharing information, a second frame of data transmitted after a secondsync pulse may include the duty cycle information, and a third frame ofdata transmitted after a third sync pulse may include the commands. Someof the information (such us the current sharing information) may betransmitted after every sync pulse, while other information (such as theduty cycle information and/or the commands) may be transmitted only whenan update is desired. In some situations, no information other than thesync pulse may be transmitted. In other situations, only the duty cycleinformation, the current sharing information, and/or the commands may betransmitted. The sync control module 212-1 may transmit one frame ofdata per PWM cycle of the power supply modules 204 and 208.

The sync control module 212-2 updates a duty cycle of the convertercontrol module 216-2 according to the duty cycle information. Further,the sync control module 212-2 receives any of the commands transmittedfrom the sync control module 212-1 and process the commands accordingly.For example, the command module 220-1 of the master power supply module204 may transmit the commands to the sync control module 212-1, which inturn transmits the commands to the sync control module 212-2. The synccontrol module 212-2 transmits the commands to the command module 220-2.The commands may include, but are not limited to, a hard shutdowncommand, a soft shutdown or reset command, a run command, and anadaptive calibration command.

Each of the power supply modules 204 and 208 further controls operationof the respective converter control modules 216 based on informationreceived from the inductor current measurement modules 228. For example,in the master power supply module 204, the inductor current measurementmodule 228-1 receives an inductor current signal 252-1, which representsa current through the inductor 124-1 (as shown in FIG. 1). The masterpower supply module 204 may control the converter control module 216-1to adjust the current through the inductor 124-1 based on theinformation received from the inductor current measurement module 228-1.The sync control module 212-1 also transmits the information receivedfrom the inductor current measurement module 228-1 to the sync controlmodule 212-2 as the current sharing information. Accordingly, the synccontrol module 212-2 is updated with the current output from the masterpower supply module 204.

Similarly, in the slave power supply module 208, the inductor currentmeasurement module 228-2 receives an inductor current signal 252-2,which represents a current through the inductor 124-2 (as shown in FIG.1). The current share control module 232-2 receives both the informationreceived from the inductor current measurement module 228-2, as well asthe inductor current measurement module 228-1 via the sync controlmodule 212-2. In other words, because the sync control module 212-1transmits the current sharing information to the sync control module212-2, the current share control module 232-2 receives informationregarding the current outputs of both the master power supply module 204and the slave power supply module 208 (i.e. the currents through each ofthe inductors 124). Accordingly, the slave power supply module 208,using the current share control module 232-2, may control the convertercontrol module 216-2 to adjust the current through the inductor 124-1based in part on the current output of the master power supply module204.

Referring now to FIG. 3, an example current share control module 300 isshown. The current share control module 300 may implement a high speedproportional-integral (PI) control scheme to reduce any imbalancebetween the current outputs of the master power supply module 204 andthe slave power supply module 208 during transient conditions (e.g. amaster inductor current and a slave inductor current). Further, thecurrent share control module 300 may implement the PI control scheme toreduce any effects of output stage resonance frequency during thetransient conditions.

The current share control module 300 includes a PI control module 304and a summing module 308. The PI control module 304 includes aproportional module 312, an integral module 316, and a summing module320. The summing module 308 receives a slave inductor current 324 and amaster inductor current 328. For example only, the received slaveinductor current 324 may be a first voltage V_(ind) that represents theslave inductor current and the received master inductor current 328 maybe a second voltage V_(target) that represents the master inductorcurrent. The received master inductor current 328 corresponds to atarget inductor current of the slave power supply module 208. Thesumming module 320 outputs a difference (i.e. error) 332 between theslave inductor current 324 and the master inductor current 328. Forexample only, a voltage V_(e) corresponds to the error 332.

Each of the proportional module 312 and the integral module 316 receivesthe error 332. The proportional module 312 and the integral module 316calculate and output a proportional term 336 and an integral term 340,respectively, based on the error 332. The summing module 320 sums theproportional term 336 and the integral term 340 and outputs a currentshare correction 344 accordingly. For example only, a voltage V_(share)corresponds to the current share correction 344. The current sharecorrection 344 corresponds to an output of the current share controlmodule 232-2 as shown in FIG. 2.

The PI control module 304 updates the current share correction 344 at arate that is limited only by characteristics of the output stages (i.e.the converters 104) and a sampling rate of the current share system 200(e.g. sampling rates of the inductor current measurement modules 228).For example only, the current sharing information including the masterinductor current 328 may be provided at every PWM cycle of the powersupply modules 204 and 208.

In the PI control module 304 of the present disclosure, coefficients ofthe PI control module 304 are selected based on information provided viathe current sharing information. In other words, the slave inductorcurrent 324 and the master inductor current 328 provide informationregarding the output stages of the master power supply module 204 andthe slave power supply module 208. For example only, characteristics ofthe PI control module 304 may be matched to an output stage resonancefrequency of the converters 104. Consequently, effects of the outputstage resonance frequency are reduced and the transient response issmoothed.

For example only, a zero z_(i) of the PI control module 304 is selectedto match (i.e. sit on top of) the output stage resonance frequency and apole of the PI control module 304. Accordingly, a gain kp_(share) of theproportional module 312 is selected such that the zero z_(i) of the PIcontrol module 304 matches the output stage resonance frequency. A gainki_(share) of the integral module 316 can be set to 1 to simplify bothcalculations and hardware implementation of the PI control module 304.

For example, where

${\frac{V_{share}}{V_{e}} = \frac{{kp}_{share}\left( {z - z_{i}} \right)}{z - 1}},$

z_(i) can be isolated according to

$z_{i} = {\frac{\left( {{kp}_{share} - {ki}_{share}} \right)}{{kp}_{share}}.}$

A desired value of z_(i) is determined based on the output stageresonance frequency wT_(share). The resonance frequency wT_(share) iscalculated according to a sampling period that corresponds to a PWMperiod T_(PWM) of both the master power supply module 204 and the slavepower supply module 208, an output inductance L, and an outputcapacitance C. Accordingly,

${{wT}_{share} = \frac{\left( {2 \times T_{PWM}} \right)}{\sqrt{LC}}},$

and z_(i) is selected to match wT_(share). With the desired value ofz_(i) known and the gain ki_(share) of the integral module 316 set to 1,kp_(share) can be further simplified according to

${kp}_{share} = {\frac{1}{1 - z_{i}}.}$

Consequently, the gain kp_(share) of the proportional module 312 can beset to match the zero z_(i) of the PI control module 304 to the outputstage resonance frequency wT_(share).

Referring now to FIG. 4, an example current share method 400 begins at402. For example only, the method 400 may power on the current sharesystem 200 as shown in FIG. 2. At 404, the method 400 determines whethera sync pulse is detected. If true, the method 400 continues with 406. Iffalse, the method 400 repeats 404 to continue determining whether a syncpulse is detected. Alternatively, the method 400 may determine that acorresponding power supply module is not in a current share arrangementif no sync pulse is detected in a predetermined period, and terminatethe method 400. At 406, the method 400 beings operation according to thesync pulse.

At 408, the method 400 determines whether any of a second type ofinformation is detected. For example only, the method 400 determineswhether current sharing information, duty cycle information, and/orcommands are detected. If true, the method 400 continues with 410. Iffalse, the method 400 continues with 404. Alternatively, the method 400may repeat 408 to continue to determine whether any of the second typeof information is detected for a predetermined period before returningto 404. At 410, the method 400 adjusts control of the current sharesystem 200 based on the second type of information. For example, themethod 400 may adjust a duty cycle based on the current sharinginformation and/or the duty cycle information. At 412, the method 400determines whether to terminate the current share method 400. If true,the method 400 ends at 414. If false, the method 400 continues at 404 todetect a next sync pulse.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification, and the following claims.

1. A current share system for providing current to a load, the currentshare system comprising: a first power supply module that controls afirst voltage converter to provide a first current to the load, thattransmits synchronization information using a first pin, and thattransmits at least one second type of information using the first pin;and a second power supply module that receives the synchronizationinformation at a second pin, that receives the at least one second typeof information at the second pin, and that controls a second voltageconverter to provide a second current to the load based on thesynchronization information and the at least one second type ofinformation.
 2. The current share system of claim 1 wherein a digitalsignal includes the synchronization information and the at least onesecond type of information.
 3. The current share system of claim 1wherein the second type of information includes at least one of currentsharing information, duty cycle information, and commands.
 4. Thecurrent share system of claim 1 wherein the second type of informationincludes duty cycle information, and wherein the second power supplymodule adjusts a duty cycle of the second voltage converter based on theduty cycle information.
 5. The current share system of claim 1 whereinthe synchronization information includes synchronization pulses and thesecond type of information includes a frame of data.
 6. The currentshare system of claim 5 wherein the frame of data is transmitted betweenconsecutive ones of the synchronization pulses.
 7. The current sharesystem of claim 1 wherein: the at least one second type of informationincludes current sharing information corresponding to the first current;and the second power supply module receives the current sharinginformation, receives a signal corresponding to the second current, andadjusts the second current based on the current sharing information andthe signal.
 8. The current share system of claim 7 wherein the secondpower supply module adjusts the second current further based on anoutput stage resonance frequency of the current share system.
 9. Thecurrent share system of claim 7 wherein the second power supply moduleincludes a proportional-integral (PI) control module that adjusts thesecond current, and wherein a proportional gain of the PI control moduleis selected such that a zero of the PI control module matches an outputstage resonance frequency of the current share system.
 10. The currentshare system of claim 9 wherein an integral gain of the PI controlmodule is set to
 1. 11. A method for operating a current share systemfor providing current to a load, the method comprising: using a firstpower supply module, controlling a first voltage converter to provide afirst current to the load; transmitting synchronization informationusing a first pin of the first power supply module; transmitting atleast one second type of information using the first pin; receiving thesynchronization information at a second pin of a second power supplymodule; receiving the at least one second type of information at thesecond pin; and using the second power supply module, controlling asecond voltage converter to provide a second current to the load basedon the synchronization information and the at least one second type ofinformation.
 12. The method of claim 11 wherein a digital signalincludes the synchronization information and the at least one secondtype of information.
 13. The method of claim 11 wherein the second typeof information includes at least one of current sharing information,duty cycle information, and commands.
 14. The method of claim 11 whereinthe second type of information includes duty cycle information, andwherein the second power supply module adjusts a duty cycle of thesecond voltage converter based on the duty cycle information.
 15. Themethod of claim 11 wherein the synchronization information includessynchronization pulses and the second type of information includes aframe of data.
 16. The method of claim 15 further comprisingtransmitting the frame of data between consecutive ones of thesynchronization pulses.
 17. The method of claim 11 wherein the at leastone second type of information includes current sharing informationcorresponding to the first current, and further comprising: receivingthe current sharing information using the second power supply module;receiving a signal corresponding to the second current using the secondpower supply module; and adjusting the second current based on thecurrent sharing information and the signal using the second power supplymodule.
 18. The method of claim 17 further comprising adjusting thesecond current further based on an output stage resonance frequency ofthe current share system using the second power supply module.
 19. Themethod of claim 17 wherein the second power supply module includes aproportional-integral (PI) control module, and further comprising:adjusting the second current using the PI control module; and selectinga proportional gain of the PI control module such that a zero of the PIcontrol module matches an output stage resonance frequency of thecurrent share system.
 20. The method of claim 19 further comprisingsetting an integral gain of the PI control module to 1.